The goal is to continue our past efforts to define the locations, internal organizations, and anatomical connections of the parts of the somatosensory system in primates devoted to the teeth and oral cavity. Much progress has been made in which studies have focused on the organizations and connections of tooth representations in anterior parietal areas of cerebral cortex. The proposed studies are aimed at three further parts of the somatosensory system, namely, cortex within the lateral sulcus (S-II region), the somatosensory thalamus, and the terminal fields of primary afferents. Specific projects are centered around five questions: (1) How many representations of the teeth and oral cavity exist in somatosensory cortex of monkeys? (2) What are the anatomical connection patterns of separate cortical tooth representations? (3) Do separate cortical tooth representations process information from the same individual neurons or groups of neurons? (4) What are the topographic organizations and connections of thalamic tooth representations? (5) How do afferent fibers from the teeth and gums distribute centrally in monkeys? Microelectrode mapping methods and anatomical tracing methods similar to those successfully used in the past period of grant support will be applied in experiments using squirrel monkeys and macaque monkeys. The long-term goal is to provide better descriptions, at all levels of the somatosensory system, of the portion concerned with processing information from the teeth and oral cavity, and to promote significantly greater understanding of how the part of this system concerned with tactile inputs might function under normal conditions.